The invention concerns a multiport valve, which, for instance, can serve for pneumatic control, intended generally for the regulation of air bags at vehicle seats.
In the usual multiport valve, a sealing element customarily is incorporated in a valve chamber in which a plurality of connecting passages communicate with openings. DE 35 03 357 discloses a multiport valve, which exhibits an operational duct that can be connected to one pneumatically functioning device and also to two pressure passages connectable to respectively different pressure sources. The connecting passages open respectively with one opening into a valve chamber, which is encapsulated by an elastic membrane and by a housing component. On the inside of the membrane are provided two sealing surfaces, that can be pressed against the opening of the respective pressure line in order to close this access.
The membrane area, which is found between the sealing surfaces, abuts itself against a pin placed in the valve housing to serve as a toggle bearing. The toggle movement of the membrane area, which possesses the sealing surfaces, is activated by a rod. This rod is seated in a recess on the membrane side in which its longitudinal axis aligns with the central, longitudinal axis of the toggle bearing.
The disadvantage of this known valve is that the activation rod must be moved in a direction specified by the position of the toggle bearing and the valve seat. Accordingly, the valve is installed in an apparatus, for instance in a control unit, in which the various possibilities for the spatial orientation of the valve are limited. This is especially problematic when a plurality of individual valves must be combined into a greater valve arrangement.
A further disadvantage of this known multiport valve is that the pin placed in the toggle bearing in the valve chamber, with its additional space requirement, makes necessary a larger valve housing and especially requires a larger area for the membrane.
Thus, the objective of the invention is to propose a multiport valve to overcome the stated disadvantages.
This objective is achieved by a multiport valve possessing the features of the invention. Accordingly, there are two connection passages communicating with one opening in the valve chamber, namely a first and a second connection passage are present. Only the opening of the first connection passage is controllable with the help of a sealing element. The sealing element, when in its inactive state, lies on the peripheral rim which forms the valve seat of the controllable opening. At the same time, the sealing element closes the complementary first opening. The sealing element is either directly or indirectly bound in such a manner with an activation means that the sealing element can be tilted away from the valve seat. During tilting, the valve seat also acts as the bearing for the toggle action.
In the case of a circularly shaped valve seat, the direction of the tilting motion of the sealing element is variable. Therefore, contrary to the requirement of DE 35 03 357, the installation orientation of the valve is not limited by a pre-determined direction of activation.
The valve seat of the controllable opening also serves as a toggle bearing, so a separate toggle bearing may also be dispensed with. As a result, a smaller valve housing and especially a smaller membrane are required, which relates favorably on the clearance space required for the installation of a valve. Another advantage is obviously found in the valve production costs. Manufacturing of the proposed valve of the invention is simplified as well.
In the case of the known valve, care must be taken as to the exact mutual positioning of the two valve seats on the membrane underside, as well as the placement of the toggle bearing. In contrast, in the case of the proposed valve, only the position of the sealing element and the controllable opening of the first connection entry must be aligned with one another.
On the other hand, the opening of the second passage can open at an optional location in the valve chamber. The same membrane for the valve body can be used with a different arrangement of the opening of the second connection passage. Particularly advantageous is a situation in which the membrane is circular in shape as seen from the top and the sealing element is placed in the center of the membrane. During assembly then, the rotational position of the membrane is not critical.
In another advantageous embodiment, the membrane and the sealing element are of one-piece construction. This step substantially simplifies the manufacture. The activation element is preferably an activation rod, which has one end embedded in a radial and axial shape-fit in a recess made in the sealing element on the membrane""s outer side. With an activation rod so affixed, then the sealing element can be either lifted up; i.e., elevated from the sealing seat, or by a deflection of the activation rod, be tilted away from the seat.
Besides the simplicity of assembly, the activation rod is particularly valuable in that the membrane need not be penetratively attached to the rod, which would otherwise exhibit sealing problems. The valve chamber space is hermetically sealed, especially when the closure element is of one-piece with the membrane.
The effectiveness of the sealing function due to the coaction of the sealing element and opening of the first connection passage is improved by a protruding valve seat rising from the surface and, ring-like, circumscribing the opening. Advantageously, the surface and the edge area which surrounds the opening is a smooth plane.
In a favorable embodiment, the sealing element is spring loaded in the closure direction in which the activation rod is enclosed within a helical spring. The spring abuts itself on one end against a housing wall and on the other end against a flange protruding radially from the activation rod. In another advantageous embodiment, an overlaying toggle top is provided, which, in the directionally pressed condition, deflects the activation rod.
A multiple port valve arrangement with at least three connection passages is possible if a plurality of the above described valves are preferably combined together in one housing. In such an arrangement, only one valve body with a common surface is provided. The connection passages communicate, respectively, with one or more openings in the surface.
The membranes of the individual valves for such a combined valve arrangement are advantageously bound together by the formation of a one-piece, general membrane. The various possibilities of a multiport valve can be increased in which the valve chambers of two neighboring membranes are bound together over one passage. The passage is admitted on the underside which lies on the common surface of the membrane sealing disk. In this way, for example, the valve chambers of two individual valves can be interconnected with a common communication passage. In a preferred valve arrangement, a circular shaped toggle top is provided, which has its bearing in a centrally located, hemispherical pin seated in a corresponding socket integral with the housing top. With this arrangement, a plurality of lever arms radiate somewhat at right angles, each coacting to deflect a respective activation rod.